Striking pad for die cutting machines



June 30, 1970 K. REICHERT 3,517,579

' STRIKING PAD FOR DIE CUTTING MACHINE Filed Oct. 2. 1968 FIG. 2

N [141445 s FIG. 3

FIG. 4

1 E1 E5 L/M. 34

g g g I INVENTOR. m A I A; l m S LEONARD K. REICHERT BY FIG. 5 VflM 3ATTORNEYS United States Patent 3,517,579 STRIKING PAD FOR DIE CUTTINGMACHINES Leonard K. Reichert, 16 Euston St., Brookline, Mass. 02146Filed Oct. 2, 1968, Ser. No. 764,406 Int. Cl. B2641 7/00 U.S. Cl. 83-5336 Claims ABSTRACT OF THE DISCLOSURE In a die cutting machine having astationary cutting bed and movable striking arm, a pad of solidresilient resinous material detachably connected to the striking arm andhaving a smooth continuous surface for direct impact with the back of aconventional die placed on stock spread on the cutting bed for cutting.

This invention relates to machines for die cutting sheet material of allkinds, namely, leather, paper, fabric, vinyl, and/ or any combinationsand/or derivatives thereof. Such machines have a stationary cutting bedupon which the stock to be cut is spread and a movable striking elementor arm by which a sharp edged die is driven by impact through the stock.

Many attempts have been made to improve the construction and performanceof such machines by employing cutting beds of all sorts anddescriptions. In US. Letters Patent No. 2,611,757, Sept. 23, 1952, willbe found a discussion of cutting beds composed of maple blocks, nylon,cellulose acetate, resinous vinyl compounds, etc.

The present invention is directed to the improvement of the strikingelement, not to the cutting bed.

I have discovered that unexpected and important improvements areachieved by providing the striking arm of a clicking press, or otherimpact die-cutting machine, with a detachable or interchangeable pad ofa solid resilient, slightly compressible material having a smoothcontinuous surface for impact upon the back of a conventional cuttingdie.

It has been found that die cutting machines so equipped lower the wholefactory cost of the die cutting process. Employment of the pad resultsin less breakage of the dies. They stay sharp for a longer period ofuse, operate with less noise and with less wear of the cutting bed.

The cutting efficiency of dies operated in such a machine is noticeablyimproved and while I do not attempt to explain the theory of thisimprovement it may be that the material of the pad is instantaneouslycompressed under the impact of the arm on the wide back of the die so asto retary completion of the full cutting movement or stroke of the die.

Various constructions may be employed for detachably securing thestriking pad of my invention to the movable striking arm of the machine.For example, dovetail guideways may be formed on or in the arm toreceive correspondingly shaped keys on the pad, or permanent magnets maybe embedded in the pad for magnetic connection with an iron strikingarm. Or the pad may be provided with a pressure-sensitive adhesivepresented on a surface area thereof or as a cover of sheet material.

These and other features of the invention will be best understood andappreciated from the following description of preferred embodimentsthereof, selected for purposes of illustration and shown in theaccompanying drawings in which:

FIG. 1 is a view in elevation of portions of a conventional clickingpress equipped with a striking pad of my invention,

3',517,579 Patented June 30, 1970 FIG. 2 is a view in elevation of astriking arm having a magnetically attached striking pad,

1:16. 3 is a fragmentary sectional view on a larger sca e,

FIG. 4 is a fragmentary view of a modified constructlon, and

FIG. 5 is a diagrammatic view showing the cutting action of one type ofdie.

While my novel cutting pad has a broad application to all die-cuttingmachines it is disclosed herein in assoclation with a well known type ofclicking press, shown for example in US. Letters Patent No. 1,629,870,Horgan, to which reference may be had for further details ofconstruction and customary manner of operation.

In FIG. 1 it may be assumed that the stationary bed 10 is supported atconvenient height by the frame 11 and that the striking arm 12 ismounted to swing transversely above the bed and to move vertically intostriking position above a die located anywhere upon sheet stock spreadupon the bed. The arm 12 may be of cast iron or of aluminum alloy asdisclosed in Letters Patent No. 1,629,870 and its striking face issubstantially rectangular in contour.

The striking pad 13 corresponds in contour with the face of the arm 12and is herein shown as detachably connected thereto by transverseundercut ways 14 secured to the face of the arm and correspondingchannels formed in the pad. A latch 15 pivoted to the arm preventslateral disengagement of the pad.

The pad 13 may be fashioned as a slab or mat of any resinousthermosetting product such as a butadieneacrylonitrile copolyer having astiff resilient texture and Shore-D hardness of 65-85. The material ofthe pad may be rendered electro conductive by admixture with carbonblack thereto, and as such is useful in a diecutting machine operatingwith electric control of the cutting stroke.

In FIGS. 2 and 3 the pad 23 is shown as detachably secured to the castiron arm 22 of a clicking press :by permanent magnets 24 which areincorporated in the pad in flush relation to its inner face.

In FIG. 2 the pad 23 is shown as provided with a facing ply 25 of paper,cloth or cellulose and this may be secured in place by a coating ofpressure sensitive cement.

In FIG. 4 the pad 33 is shown as detachably secured to the arm 32 of thepress by screws 34 deeply countersunk so as to leave clear the fullstriking area of the pad.

I do not attempt to explain a theory that would account for the veryreal advantages that have been realized by the employment of my novelstriking pad. In the case of wide back dies like that shown in FIG. 5

there may be an instantaneous compression of the pad at' In FIG. 5,position A, the die is shown as resting on the stock preparatory tocutting. In position B the die is represented as having out aboutone-third through the stock and as hesitating on account of the impactcompression of the pad, and in position C upon recovery of compressionthe die has been driven down to complete its cutting stroke.

Another advantage of employing a striking pad of relatively malleable orsoft material is that it obviates the danger of scratching the finishedsurface of the stock as it is drawn into cutting position on the cuttingbed of the machine. It sometimes happens that resilient stock drawn froma roll will bulge upwardly into contact with the striking arm and becomedamaged by a spur or ridge on an unguarded arm of metal.

The striking pad of my invention may be employed with advantage inassociation with single-edged dies as shown in FIG. 5 or withconventional double edged dies for cutting out right and left blanks.

Having thus disclosed my invention with illustrative embodiments of thesame, I claim as new and desire to secure by Letters Patent:

1. In a die cutting machine having a stationary cutting bed and arelatively movable striking arm for use with conventional ,cutting dies,the invention which consists in a striking pad of solid resilientthermosetting resinous reaction product detachably connected to thestriking arm of the machine and having a smooth continuous surface fordirect impact with the back of a conventional die placed between it andthe cutting bed.

2. A detachable striking pad as defined in claim 1 in which the said padis detachably connected to the striking arm through the medium ofundercut guideways and interfitting keys.

3. A detachable striking pad as defined in claim 1, furthercharacterized in that the detachable pad contains permanent magnetsdisposed in flush relation in its armengaging surface.

4. A detachable striking pad as defined in claim 1,

further characterized in that the material of the pad is of suchresiliency and consistency as to retard by momentary compressioncompletion of the full cutting action of a wide back die engaged by thestriking pad of the machine.

5. A detachable striking pad as defined in claim 1, furthercharacterized in that the resinous material of the pad is renderedelectro-conductive by the admixture of carbon black.

6. A detachable striking pad as defined in claim 1, furthercharacterized in that its striking face is covered by an adhesivelyattached continuous sheet of paper for direct contact with the back of acutting die.

References Cited UNITED STATES PATENTS 1,051,665 1/l9l3 Bates 33537 X1,091,707 3/1914 Reed 83534 2,611,757 9/1952 Olson et al 83--531 X3,227,024 1/1966 Krebs 83658 X FRANK T. YOST, Primary Examiner US. Cl.X.R. 8 3-65 1, 698

